Soaps have been known and used for personal hygiene for thousands of years. Commonly referred to as toilet or bath bars, soaps for personal bathing and hand and face washing have been prepared from proprietary formulations of sodium and potassium soaps of fatty acids containing about 8 to 20 carbon atoms and other ingredients which improve the texture, appearance, and cleaning performance of bars. Plasticizing agents, perfumes and/or deodorants, antimicrobial agents, inert inorganic fillers or builders and other surfactants are commonly added.
While the body's physiologic pH is 7.4, the skin's physiologic pH is 5.5. Maintenance of the skin's normal pH is critical for the health of the skin. Disruption of the pH by typical soaps results in reduced barrier function of the stratum corneum, and create a more favorable environment for pathogenic bacteria.1 Alkaline soaps alter the pH of the skin, from a physiologic 5.5 to the level of the soap, which may higher than 10. This results in an injury to the barrier function of the skin, increased susceptibility to environmental irritants and antigens, skin irritation with erythema and edema, reduction of water content and smoothness of the skin, and an alteration of the physiologic bactericidal and fungicidal capabilities of skin.2 Chronic use of alkaline soaps is associated with more irritation than acidic syndets.3 Specifically, alkaline soaps cause swelling of the stratum corneum, affecting both structural proteins and lipid matrix.4 Alterations in skin pH play a role in the pathogenesis of irritant contact dermatitis, atopic dermatitis, ichthyosis, acne vulgaris and Candida albicans infections. The use of skin cleansers with the pH of 5.5 may prevent and treat those skin diseases5 and aid in wound healing.6 
Traditional alkaline soaps, alkali salts of fatty acids, are the predominant skin cleaner on the market. These significantly increase the pH of the skin while acidic skin cleaners do not significantly alter the pH.7 Cleansers with pH of 5.5 do not interfere with the microflora of the skin and irritate the skin less than alkaline soaps.8 
In clinical studies, acidic cleansers are less irritating than alkaline soaps9 and can improve the disease state of contact dermatitis. Acidic cleansers reduce the levels of Staphylococcus aureus and Candida yeast on the skin10,11 
Preservatives are typical toxic components of skin care products. 14% of the population is allergic to one or another preservative12 manifesting as contact dermatitis which injures the barrier function of skin and sets up a condition that increases the toxicity of other skin care components, in addition, many preservatives are proven endocrine disrupters and suspected carcinogens.13 As used in this specification, “performance” in bar skin cleaners is a function of skin cleaning ability, lather, “slip” (slide of the bar across the skin), and bar integrity.
Generally prepared from sodium and potassium fatty acid mixtures derived from natural fats and oils such as tallow, coconut oil, palm oil, palm kernel oil, soybean oil and the like, sodium fatty acid soaps are usually harder than potassium fatty acid soaps, and soaps of saturated fatty acids are harder than those prepared from unsaturated fatty acids. Accordingly, the hardness of fatty acid soaps increases with the length of the fatty chain. Most commercial toilet soap bars contain major amounts of sodium soaps of saturated fatty acid mixtures with minor amounts of potassium soaps and unsaturated fatty acid soaps to alter the feel, texture, appearance and wearability or resistance to cracking and discoloration of the bar. Petrolatum is a commonly used binding agent that helps hold the bar together. Petrolatum is an oil-based product with polycyclic aromatic hydrocarbons that have been implicated in carcinogenesis. Harsh surfactants such as sodium lauryl sulfate (SLS) are commonly used to improve performance, particularly “lather”. SLS is a skin irritant for 100% of humans.
Due to these disadvantages, there has been a trend in the industry to manufacture toilet bars from blends of sodium and/or potassium soaps and compounds classified in the art as synthetic detergents (“syndets”) or surfactants. There are also many commercially available bars prepared from these synthetic detergent compounds entirely devoid of the traditional fatty acid soaps. See for example U.S. Pat. Nos. 2,894,912; 2,781,320; 3,154,494; 3,186,948; 3,223,645; 3,224,976; 3,226,330. The specific compositions of many synthetic detergent and soap-synthetic detergent bars, usually referred to as combination bars in the industry, vary greatly, the majority of formulations being proprietary to the particular manufacturer.
In part, because the detergent industry has sought to produce toilet bars having improved appearance, texture, feel, scent, color and wearability acceptable to most consumers, they have ignored one of the most basic requirements for soap to be used on human skin: that is the skin's natural pH of 5.5 and inherent barrier oils and properties. Soap with a pH over 7 disturbs the natural anti-bacterial properties of sebum allowing for a proliferation of bacteria and yeast, particularly S. aureus and P. aeruginosa. This elevation of pH can last as long as 6 hours before natural homeostatic processes return the skin's natural pH to 5.5. Hence use of an alkaline facial scrub can actually promote bacterial proliferation and acne.
Some formulators have sought to produce synthetic detergents (referred to hereafter as “syndets”) which are non-alkaline, preservative free, and contain no dyes, yet which provide the performance, i.e. feel, scent, froth and color, of traditional soaps. Unfortunately, providing a cleanser which froths and is still non-alkaline has been heretofore unachievable without resorting to the use of sodium lauryl sulfate (hereafter referred to as “SLS”), relatives thereof, and other irritating surfactants to achieve the frothing which consumers associate with good cleansing. Application of SLS and other similar surfactants on the skin can degrade the “barrier function” of the skin. The consequences of this are increased penetration of toxins that can damage the skin, the body as a whole, and have been shown to cause the skin to produce sebum and other oils as well as local inflammation that are anathema to achieving the healthiest skin possible.